This invention relates to video signal processing. More specifically, this invention concerns real time processing of video signals for the purpose of creating a three dimensional effect.
Three dimensional or stereoscopic viewing generally requires the production of disparate left and right images. Most conventional three dimensional techniques produce images which are not compatible, i.e. which cannot be viewed comfortably without specially filtered glasses. Songer (U.S. Pat. No. 3,712,199) has disclosed an anaglyph (i.e. color encoded) stereoscopic system capable of producing a compatible three dimensional image. The image is compatible in that when it is viewed without the specially filtered glasses required for stereoscopy, it is seen as an acceptable two-dimensional image.
In Songer, image separation (sometimes referred to as binocular disparity) is created by a color fringing effect on the out-of-focus objects. For example, objects fore of the plane of focus may be imaged with a magenta defocus blur on the left side and a cyan defocus blur on the right side. Objects aft of the plane of focus will be encoded in the opposite sense, i.e. cyan on the left and magenta on the right. When viewed through appropriately filtered glasses, disparate out of focus images are seen causing the viewer to perceive what is termed by Songer as "psychophysiological 3-D". Without the glasses, the defocus blurs are barely noticeable and the image is perceived as a normal two-dimensional picture.
Although Songer's system is applicable to television, it has certain drawbacks which limit its applicability to this medium. In the first place, since image disparity is created by a defocus blur, a lens system with very low depth of focus (e.g. telephoto lenses) will not produce sufficient color fringing to create a three dimensional affect. Such lenses are frequently used for television, particularly for sporting events.
Secondly, the cost involved in modifying existing television cameras in accordance with the Songer system is prohibitive.